1. Field of the Invention
The present invention relates to garments and other covers used to protect against passage of air and water.
2. Description of Related Art
Conventional gloves made from silicone or other "rubber" elastomer have proven to be relatively good protective barriers. These products are quite impermeable to most contaminants and are inexpensive enough to be discarded after each use. However, rubber gloves have a number of deficiencies, including being impermeable to moisture vapor (making them very uncomfortable to wear for long periods of time), being subject to deterioration when exposed to certain chemicals or other adverse environmental conditions, and being prone to puncture and tears.
One answer to the uncomfortable nature of conventional rubber gloves is to employ gloves made from a waterproof and breathable material, such as expanded polytetrafluoroethylene (PTFE) made in accordance with U.S. Pat. No. 3,953,566 to Gore. Expanded PTFE as a membrane comprises a lattice of polymeric nodes and interconnected fibrils that creates an effective microporous barrier. This barrier repels water and other liquids while allowing moisture vapor to escape. A barrier of expanded PTFE has also been demonstrated to be quite effective at isolating contaminants, such as microorganisms.
Gloves, and glove inserts made from expanded PTFE and fabric composites are commercially available under the trademark GORE-TEX from W. L. Gore & Associates, Inc., Newark, Del. For many uses these gloves are considered to be the state-of-the-art in waterproof/breathable protection. Despite their effectiveness in a wide variety of applications, it has now been determined that at least certain gloves made from this composite do not consistently pass certain highly demanding tests, such as those for microbial protection. While these gloves are thoroughly waterproof through both the membrane and the seams, according to certain tests it has been determined that some penetration can occur through these gloves over an extended period of time. Further study has demonstrated that, although the composite material in these gloves does present a successful shield, surprisingly it is the seams of these gloves that are prone to leakage under heavy demands.
Conventional seams in expanded PTFE and fabric composites are generally formed by applying a bead of adhesive between fabric layers and sealing the seams together, sometimes under some elevated heat and pressure. Another approach in seam construction is to apply high heat and pressure to a polymeric coating so as to melt-flow and bond two layers together. Despite the effectiveness of these approaches in avoiding water penetration, it has been determined that these seams are not effective strong barriers to sub-microscopic contaminants, such as viruses suspended in a body fluid simulant (42.+-.2 dynes/cm), or liquid over an extended period of exposure.
Previous glove inserts used in ski gloves and similar applications are not consistently airproof as measured by a "Whole Glove Leak Tester" (WGLT). While these inserts are waterproof as measured by a 5 minute dunk test (see ANSI/NFPA 1973 "Gloves for Structural Fire Fighting" test Chapter 5-12), and a 1 minute fill test, these inserts are not durably waterproof as measured by 1 hour wicking dye test.
Inserts used in military applications are airproof as measured by the WGLT and waterproof as measured by a 15 minute water fill test. However, these inserts are not durably waterproof as measured by the 1 hour wicking dye test.
Most recently, the United States has raised its standards for leakage protection, requesting that the glove should be able to pass a 24 hour wicking dye test. Until the present invention, no previous glove construction could assure compliance with such a rigorous standard.
Accordingly, it is a primary purpose of the present invention to provide an improved protective cover that is comfortable to wear yet provides a durable and highly effective barrier to air and water penetration.
These and other purposes of the present invention will become evident from review of the following specification.